This invention relates generally to fuel pressure regulator valves of the type used in automobile engine fuel injection systems, and more specifically it relates to an improvement in retention of the diaphragm-carried valve element of such valves.
A common type of fuel pressure regulator valve comprises a housing in which a diaphragm assembly divides the housing into two chambers, one of which is a control chamber and the other of which is a fuel chamber. The fuel chamber has an inlet which is in communication with pressurized fuel whose pressure is to be regulated and an outlet through which excess fuel is returned to the tank. The diaphragm assembly carries a valve element that coacts with a valve seat that is disposed in the fuel chamber. The valve seat is provided on the inner end of the outlet from the fuel chamber. The control chamber controls the pressure of fuel in the fuel chamber that will cause unseating of the valve element from the valve seat and in this way regulates the pressure of the liquid fuel to which the inlet is communicated. The control chamber comprises a helical spring that acts on the diaphragm assembly such that the valve element is biased toward seating on the valve seat and hence toward blocking flow between the inlet and outlet. The control chamber further comprises a control port that is communicated to a vacuum control. Application of vacuum to the control chamber acts on the diaphragm assembly in the direction opposite that of the spring. By suitable control of the vacuum that is delivered to the control chamber, the pressure in the fuel chamber at which unseating of the valve element occurs is controlled. In this way, the valve performs the function of regulating the pressure of liquid fuel to which the fuel chamber inlet is exposed.
One known form of valve element comprises a truncated metal sphere which has an overall size greater than a hemisphere and which has a flat circular face at the truncation. The truncated sphere is retained on a metal mount carried by the diaphragm assembly such that it is the flat circular face that coacts with the valve seat and such that the truncated sphere is able to swivel within the mount. The swivelling capability assures that the flat circular face of the truncated sphere will properly seat on the valve seat to block fuel flow from the fuel chamber outlet when such blockage is intended. The truncated sphere is secured on the metal mount by disposing the sphere in a cavity formed in the mount and then swaging, or crimping, a flange that surrounds the cavity over the sphere.
This swaging, or crimping, is an operation that must be relatively carefully controlled because it is necessary for the sphere to have a certain limited amount of travel when captured within the cavity of the mount. Hence manufacturing tolerances must be carefully monitored during the manufacturing process, and adjustments made as required, so that each sphere is within the allowable limits of travel within the mount cavity after swaging. Such procedures have been found to contribute significantly to manufacturing cost.
Another known form of valve element comprises a circular disk that has been soldered to a fully spherical ball. The ball is captured within the mount cavity by a comparatively complex stamping, and the step of soldering the disk to the ball is an extra operation. Hence this construction has certain disadvantages.
The present invention relates to a new and unique construction for retaining a truncated spherical valve element in the mount cavity. Briefly, the construction comprises a circular recess that is disposed around the cavity opening and has a diameter exceeding that of the cavity opening, and a circular washer disposed within the circular recess to retain the truncated sphere within the cavity, wherein the circular washer has an inside diameter greater than the diameter across the circular face of the truncation but less than the nominal diameter of the sphere, and wherein a flange around the circular recess is crimped onto the outside diameter of the circular washer. The tolerance of the inside diameter of the washer is closely controlled to provide close control of the amount of travel of the sphere within the mount cavity. This construction provides manufacturing advantages over both types of prior valve elements described above.
The foregoing, along with additional features, advantages, and benefits of the invention, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.